Just a quick, one pass over the material,top and bottom, not the batting. That is enough to anchor the lot. I then leave it for 24 hours before quilting it, to give it enough time to dry. I find it the best method that I have used.
If you are using a polyester batting, you should not spray on it as the glue (or aerosols in it) will melt or dissolve it. I only ever spray onto the material and then stick it to the batting.There is usually not a problem as I use cotton or wool batting.